The term "Meniere's Disease" is ambiguous. In
one sense, it means that one has the symptoms (either typical or
atypical) that are the same for a whole slew of diseases and
conditions (including Meniere's Disease), but testing for all
diseases and conditions other than Meniere's Disease turns out
negative. (See our diagnosis page.)
Since there is no definitive test for Meniere's Disease, the
conclusion (by "excluding" all "testable" and tested diseases and
conditions) is that the patient must have "Meniere's Disease." In
this sense, "Meniere's Disease" means "we don't know what is causing
the symptoms."
In another sense, the majority of authoritative sources will
conclude that "we don't know" Meniere's Disease is tantamount to (or
even equal to) "idiopathic endolymphatic hydrops" (IEH).
"Idiopathic" means "cause unknown." Therefore, when Meniere's
Disease is taken to mean "idiopathic endolymphatic hydrops," it
means that the patient has been diagnosed with "endolymphatic
hydrops from unknown causes." A minority of authoritative sources
will say, "we don't know what is causing the symptoms, so we will
say that the patient has 'Meniere's Disease,' which may or may not
be idiopathic endolymphatic hydrops or microvascular compression
syndrome or something else." See the main story in
this
newsletter (.pdf file), which questions the role of
endolymphatic hydrops in Meniere's Disease.
A diagnosis of Meniere's Disease or "idiopathic endolymphatic
hydrops" means that, by definition ("idiopathic"), no one knows the
cause. Such a diagnosis makes the issue of causation problematic,
whether it be in connection with an automobile accident or other
head injury, or in connection with military service, or in
connection with employment. In other words, under this
scenario, when one has Meniere's Disease, one cannot say it was
"caused" by anything.
If one is diagnosed with endolymphatic hydrops
that results from some known cause, such as head trauma or some
other cause, then one would have simply "endolymphatic hydrops" (EH)
or "traumatic endolymphatic hydrops" (TEH) or "secondary
endolymphatic hydrops" (SEH) (where endolymphatic hydrops is
"secondary" to the trauma or some other cause) or, if there is a
delay in the onset of endolymphatic hydrops resulting from the
trauma or some other cause, "delayed endolymphatic hydrops" (DEH).
(See our diagnosis page.) All
this can be confusing, especially because a few authorities use the
term "post-traumatic Meniere's Disease," which we find paradoxical.
Click here to search PubMed for post-traumatic and Meniere's or
endolymphatic hydrops.
But sometimes doctors are just imprecise with
their terminology, or doctors' employees are just imprecise with
encoding insurance claim forms, and endolymphatic hydrops that
results from some known cause, such as head trauma or some other
case, is erroneously described as "Meniere's Disease."
While these distinctions may make little
difference to some, or may be of no interest to others, they are of
major importance when causation is of legal consequence in terms of
damages or benefits. In such cases, it becomes particularly
important to have a doctor who specializes in or otherwise has a
great deal of experience in diagnosing and treating all forms of
endolymphatic hydrops, Meniere's Disease and otherwise, and knows
the differences between them. And, as always, we recommend
multiple medical opinions. (See our
doctors page.)
Cause (etiology).
Meniere's Disease is "idiopathic"
-- the etiology (cause) of the condition that gives rise to
Meniere's Disease symptoms is
unknown, although there is a great deal of
research under way.
"Unknown" as in "unknown."
As in *really, really* unknown.
Nature of the condition.
There is disagreement over the
nature of the condition that gives rise to Meniere's Disease
symptoms.
Some researchers believe that
Meniere's Disease is one thing and one thing only: idiopathic
endolymphatic hydrops. Other authorities believe that *some*
cases of Meniere's Disease are idiopathic endolymphatic hydrops and
that *other* cases have other etiologies (causes).
Idiopathic endolymphatic hydrops (IEH).
According to the prevailing, but
not definitive, theory, Meniere's Disease is "idiopathic
endolymphatic hydrops."
"Idiopathic" means that the
cause is unknown.
If the cause of your symptoms is
known, your condition cannot be "idiopathic endolymphatic
hydrops," by definition. If Meniere's Disease is the same
as "idiopathic endolymphatic hydrops," and the cause of your
symptoms is known, then you cannot have Meniere's Disease, by
definition.
"Endolymphatic" refers to
endolymph, one of two fluids in the cochlea in the inner ear.
(The other fluid is perilymph.)
"Hydrops" means excessive
fluid build-up (dilatation). Think: swelling.
"Idiopathic endolymphatic
hydrops" means the "cause unknown build-up of excessive
endolymphatic fluid in the cochlea located in the inner ear."
See the main story in
this newsletter (.pdf) from an agency within the National
Institutes of Health, in which an article questions the role of
endolymphatic hydrops in Meniere's Disease.
Endolymphatic hydrops (EH).
The term "endolymphatic hydrops"
(EH) encompasses both the "idiopathic" (cause unknown) form,
which most, but not all, authorities consider to be Meniere's
Disease, and the several non-idiopathic forms, in which the cause
is known.
Idiopathic endolymphatic hydrops
(IEH).
This is Meniere's Disease,
according to most, but not all, authorities. See above.
Non-idiopathic endolymphatic
hydrops. There are several forms of endolymphatic
hydrops that are not idiopathic because the cause is known and,
since the cause is known, these forms of non-idiopathic
endolymphatic hydrops are *not* Meniere's Disease.
"Secondary endolymphatic
hydrops" (SEH).
The endolymphatic hydrops in
SEH is "secondary" or following from a known cause. For
example,
this case in which endolymphatic hydrops was said
to be secondary (followed from) perilymph fistula.
According to
this article, TEH is "an accumulation of endolymph
in the cochlear duct caused by traumatic insult.
According to the article, "The diagnosis of traumatic
endolymphatic hydrops is made by a history of trauma, such as
barotrauma, a blow to the head, or perhaps a previous ear
operation, such as stapedectomy; the presence of typical
symptoms of endolymphatic hydrops, including fullness,
tinnitus, fluctuant hearing loss, and episodic vertigo; and an
elevated negative summating potential and an increased
summating potential:action potential ratio by
electrocochleography."
In the absence of observable
physical damage, or an obvious explanation in one's medical
history, one's endolymphatic hydrops is likely to be attributed
to Meniere's Disease, meaning idiopathic endolymphatic hydrops.
Some authorities believe that, at
least in some cases, the symptoms of Meniere's Disease may result
from physical pressure of a blood vessel upon the
vestibulocochlear (8th cranial) nerve, causing the nerve to
compress. Thus, they believe, relief may be obtained through
microvascular decompression (MVD) -- microsurgery to move blood
vessels off of the vestibulocochlear nerve. Some doctors
believe that MCS is a separate disease.
Symptoms can be induced or exacerbated
by "triggers."
Many patients can identify "triggers"
that induce or exacerbate their symptoms. "Triggers"
are not causes. To the extent that patients can
identify and avoid or treat triggers, they can reduce, but
not eliminate, their discomfort from symptoms. Some
patients cannot identify any triggers.
Meniere's Disease
cannot be traced
genetically; it is not hereditary and it is not inherited. However, the incidence
is slightly
higher in some families for reasons not understood;
thus, Meniere's Disease is sometimes said to be
"familial."
"Herpes" is a family of viruses.
Herpes simplex virus (HSV) is the virus that causes "oral herpes
(cold sores)" and "genital herpes." There are two types,
Type 1 and Type 2. Either type can cause infections in
either location, but so far most oral herpes are caused by Type 1
and most genital herpes are caused by Type 2. Both types are
contagious and can be transmitted to either location.
Yet another herpes virus, the
Epstein-Barr virus, causes infectious mononucleosis ("kissing
disease").
A very few studies have found a
vaguely possible link between HSV and Meniere's Disease, but these
studies merely conclude that yet more study is needed. HSV
has NOT been established as "the cause" or even "a cause" of
Meniere's Disease. According to the
U.S. National Institutes of Health, 90% of American adults
have antibodies for HSV type 1, and 30% of American adults
have antibodies for HSV type 2, but only a tiny percentage of
either group develop Meniere's Disease. There are people who
have no antibodies to HSV but who have developed Meniere's
Disease. No study in
PubMed states for a fact that HSV is a cause of Meniere's
Disease.
Nonetheless, we are hearing
anecdotal reports from patients that a few doctors are offering
antiviral drugs that are usually used to treat herpes simplex
virus (and other viruses) to treat some Meniere's Disease.
Read more in the antiviral
drug section of our Treatment Page.
Some cases of Meniere's Disease
are believed by some authorities to be autoimmune in origin,
simply because the symptoms in these cases respond to
immunosuppressant drugs such as prednisone, methotrexate, and
others (see ourtreatment page).
There is a fine line between autoimmune-mediated Meniere's
Disease and Autoimmune Inner Ear Disease (AIED).
Meniere's Disease is not known to
be contagious in any way.
Post hoc ergo propter hoc.
Although the cause of Meniere's
Disease is unknown, many patients spend considerable time trying
to guess at what "gave" them Meniere's Disease.
If there were a known cause for
one's symptoms, one wouldn't have Meniere's Disease, because
Meniere's Disease has no known cause and no known origin.
It seems to be the nature of
humanity that it seeks "reasons" for everything. People
seek "reasons" for their diseases. The mysterious nature of
Meniere's Disease seems particularly to make people seek "the
reason" that they have been so afflicted. Without a
attributed reason for their Meniere's Disease, they lack
"closure." Patients often try to find some event to which
they can attribute their Meniere's Disease. Suspects
include: automobile accidents, military service (even three
or more decades earlier), ear infections during youth, travel to
foreign countries, prescription or illegal drugs, and more.
The practical reality is that, in the absence of observable
physical damage (for example, a crushed skull or a gunshot wound),
there is unlikely to be any provable association, and one's
endolymphatic hydrops is likely to be dubbed "Meniere's Disease."
While patients may convince themselves of a cause of their
Meniere's Disease, the reality is that no one knows the cause of
anyone's Meniere's Disease.
There is a logical fallacy,
post hoc ergo propter hoc (after this, therefore because of
this), to which Meniere's Disease patients often fall victim.
That is to say that patients, having settled upon some event that
preceded their Meniere's Disease symptoms, become convinced merely
because of the timing that the event is the "cause" of their
Meniere's Disease. This is quite understandable, but
scientists will likely conclude that while causation is possible
(in the sense that alien abductions are possible), there is no
proof of causation. Click
here for a Google search on the fallacy of post hoc
ergo propter hoc. The reality is that most of us will
never know what caused our endolymphatic hydrops.
Discussions: cause (etiology) of Meniere's Disease.
The
Winter
2005 (.pdf) issue of the newsletter of the
National Temporal
Bone Registry features an article entitled, "Meniere's Syndrome:
Are Symptoms Caused by Endolymphatic Hydrops?"
Our lay
and inexpert speculation: perhaps there are ten (or more or fewer)
currently unknown diseases that each have the same symptoms as what
we now call "Meniere's Disease," and we each have one (or perhaps
two or three) of the ten (or more or fewer) of the currently unknown
diseases. *IF* this is true, then ten patients could be diagnosed
with "Meniere's Disease," yet each one could have a different
disease, and each one could respond differently to various
treatments.
Epidemiology (incidence and
prevalence) (frequency) of Meniere's Disease.
Studies vary widely, and
no one really knows the incidence and prevalence of
Meniere's Disease.
Meniere's Disease is no longer
listed
as a rare disease by the U.S. National Institutes of Health,
Office of Rare Diseases Research.
Anatomy.
Here are some sites that will help
you to understand the anatomy of the inner ear and of Meniere's
Disease.
Article, Los Angeles Times, May 16, 2005, health section.
The print edition has the best graphic illustrating the location and
relationship of endolymph and perilymph that we've ever seen (kudos
to the L.A. Times artist, Paul Rodriguez). (Disclosure:
the MDIC was a source.) Unfortunately, the graphic is not
available online.
Washington
University. The opening graphic
demonstrates the relationship between endolymph and perilymph (inner
ear fluids). Endolymph is the operative fluid in
Meniere's Disease.
